From my own experience, FB ads is the easiest way to go. You can just let FB optimize your CPM and get decent likes/$ ratio. Remember to buy a coupon from fiverr, that will help you a lot. I'm not experienced enough to mentor you.

Ok, well, I wouldn't recommend you 7search because many people say it's shit, I never heard anything about Bing, but it's not really that popular, so if you have to choose from these 3, I would say Facebook is the best choice, but keep in mind their rates are quite high. I would recommend you reading a LOT of guides, case studies and explanations before you go into CPC/PPV marketing, one blog I would recommend you to read is Luke Kling's, he owns a CPA network called Peerfly, his blog is http://www.lukepeerfly.com/ and you can find LOTS OF USEFUL information there, especially for Facebook/Bing.